U.S. patent application number 12/084071 was filed with the patent office on 2009-08-27 for method for operating a combustion engine.
This patent application is currently assigned to ROBERT BOSCH GMBH. Invention is credited to Markus Hernier, Karsten Mann.
Application Number | 20090211825 12/084071 |
Document ID | / |
Family ID | 37429299 |
Filed Date | 2009-08-27 |
United States Patent
Application |
20090211825 |
Kind Code |
A1 |
Mann; Karsten ; et
al. |
August 27, 2009 |
Method for Operating a Combustion Engine
Abstract
A method for operating a combustion engine, in which at least
one electric motor for providing drive assistance is activated at
least intermittently in a normal driving mode having a requested
drive power. It is provided that the combustion engine is operated
selectively in steady-state or dynamic fashion as a function of a
selected combustion process.
Inventors: |
Mann; Karsten; (Stuttgart,
DE) ; Hernier; Markus; (Gerlingen, DE) |
Correspondence
Address: |
KENYON & KENYON LLP
ONE BROADWAY
NEW YORK
NY
10004
US
|
Assignee: |
ROBERT BOSCH GMBH
Stuttgart
DE
|
Family ID: |
37429299 |
Appl. No.: |
12/084071 |
Filed: |
September 18, 2006 |
PCT Filed: |
September 18, 2006 |
PCT NO: |
PCT/EP2006/066454 |
371 Date: |
March 11, 2009 |
Current U.S.
Class: |
180/65.275 ;
123/2; 123/299; 123/672; 180/65.21 |
Current CPC
Class: |
Y02T 10/6286 20130101;
F02D 41/3035 20130101; B60W 10/06 20130101; B60W 10/08 20130101;
B60W 20/10 20130101; Y02T 10/62 20130101; B60W 2710/0616 20130101;
B60W 30/1882 20130101; B60W 20/00 20130101 |
Class at
Publication: |
180/65.275 ;
123/672; 123/299; 123/2; 180/65.21 |
International
Class: |
B60W 10/04 20060101
B60W010/04; F02D 41/00 20060101 F02D041/00; F02B 3/00 20060101
F02B003/00; F02B 63/00 20060101 F02B063/00; B60W 20/00 20060101
B60W020/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 25, 2005 |
DE |
10 2005 051 002.7 |
Claims
1-11. (canceled)
12. A method for operating a combustion engine, the method
comprising: activating at least one electric motor for providing
drive assistance at least intermittently in a normal driving mode
having a requested drive power; and selectively operating the
combustion engine in a steady-state, a quasi steady-state or
dynamically as a function of a selected combustion process.
13. The method of claim 12, wherein during a steady-state operation
of the combustion engine, a dynamic power component of the
requested drive power is provided by an electric motor.
14. The method of claim 12, wherein in a dynamic operation, the
combustion engine generates at least a portion of a dynamic power
component.
15. The method of claim 12, wherein the combustion process is
selected as a function of emissions of the combustion engine.
16. The method of claim 12, wherein in a steady-state operation, a
total fuel quantity needed for a specific engine cycle is injected
directly into a combustion chamber of the combustion engine, and
thereupon ignited.
17. The method of claim 16, wherein in a dynamic operation, fuel is
injected into the combustion chamber even after ignition has
begun.
18. The method of claim 12, wherein to set an increased power
output in a steady-state operation, the combustion engine is not
fired for a brief time, and is pulled by the electric motor to a
new operating point.
19. The method of claim 18, wherein while the combustion engine is
being pulled, an air-side charge cycle of the combustion air of the
combustion engine is optimized for the new operating point.
20. The method of claim 12, wherein the steady-state operation of
the combustion engine is set in a part-load range of the combustion
engine.
21. The method of claim 12, wherein the dynamic operation of the
combustion engine is set in at least one of a high-load range, a
full-load range, and at high speeds of the combustion engine.
22. A hybrid vehicle having at least one combustion engine,
comprising: at least one electric motor for providing drive
assistance, and which is activatable at least intermittently in a
normal driving mode having a requested drive power; and setting a
dynamic operation of the combustion engine in at least one of a
high-load range, a full-load range, and at high speeds of the
combustion engine.
Description
FIELD OF THE INVENTION
[0001] The present invention is based on a method for operating a
combustion engine.
BACKGROUND INFORMATION
[0002] Hybrid vehicles, in which combustion engines and electric
motors interact in the drive train are well-known. Various systems
are familiar, such as serial hybrids in which the combustion engine
is not connected mechanically to the drive wheels, parallel
hybrids, in which the combustion engine and the electric motor (or
perhaps several electric motors) are connected mechanically to the
drive wheels, as well as mixed forms, e.g., power-split hybrids, in
which the combustion engine is both connected mechanically to the
drive wheels and also drives the electric motor.
[0003] International Patent Application No. WO 2005/012022
discusses a method for operating a hybrid vehicle having a diesel
engine, in which an electric motor assists the diesel engine when
the gears are shifted and the clutch is disengaged. The method is
used to improve the efficiency of the drive and to reduce emissions
at low speeds of the diesel engine.
SUMMARY OF THE INVENTION
[0004] A method according to the present invention is provided for
operating a combustion engine, in which at least one electric motor
for providing drive assistance is activated at least intermittently
in a normal driving mode having a requested drive power, and in
which the combustion engine is operated selectively in steady-state
or dynamic fashion as a function of a selected combustion process.
An advantageously low-emission operation of the combustion engine
is possible when a particularly low-emission combustion process can
be selected which, to be sure, exhibits a poor dynamic performance,
e.g., upon engine-load alternation; however, the electric motor is
able to provide the dynamic power components of the drive with high
dynamic performance. This can be advantageous in load ranges in
which different combustion processes cause different amounts of
emissions. The electric motor makes it possible to select an
optimal combustion process for the specific load range. One
electric motor, or perhaps two or more electric motors may be used.
The combustion process of the combustion engine may be changed in
different load ranges. The combustion engine is preferably operated
selectively in serial or in parallel or in parallel-serial or in
power-split mode with the aid of two electric motors. The
combustion engine is thereby operated with a favorable combustion
process depending on the power requirement.
[0005] In one advantageous method operation, during steady-state
operation of the combustion engine, a dynamic power component of
the requested drive power may be provided by electric motor. The
combustion engine feeds its power output into an energy store,
e.g., a battery, from which the electric motor takes its drive
energy as a function of a requested drive power and dynamic
performance. The combustion engine is operated in a favorable range
having optimized operating parameters for reducing unwanted
emissions, e.g., soot and nitrogen oxides in the case of diesel
engines.
[0006] In a further advantageous method operation, in dynamic
operation, the combustion engine generates at least a portion of
the dynamic power component. The furnishing of the power components
by electric motor and combustion engine may be optimized with
respect to the emissions of the combustion engine here, as
well.
[0007] The combustion process with which the combustion engine is
operated may be selected as a function of emissions of the
combustion engine.
[0008] In another advantageous method operation, in steady-state
operation, a total fuel quantity needed for a specific engine cycle
is injected directly into a combustion chamber of the combustion
engine and thereupon ignited. In the case of diesel engines,
particularly in the part-load range, a "homogeneous" diesel
combustion is used with special advantage (HCCI=homogeneous charge
compression ignition), which leads to a combustion extremely low in
soot and nitrogen oxides. In the HCCI operating mode, the diesel
fuel is injected directly into a combustion chamber of the diesel
engine, and the fuel-air mixture developing in the combustion
chamber is only ignited when the total fuel quantity needed for the
engine cycle in question has been injected into the respective
combustion chamber.
[0009] The "(p)HCCI" (partly homogeneous charge compression
ignition) combustion process, in which only very small quantities
of fuel are injected into the combustion chamber after the
ignition, represents an intermediate stage. Lower emissions are
obtained than when using the conventional combustion process in
this case, as well. In the HCCI combustion process, it is assumed
that the fuel in the combustion chamber is homogenized prior to the
ignition, while in the (p)HCCI combustion process, the fuel is
partially injected and homogenized prior to the ignition, and is
partially first injected into the combustion chamber after the
ignition. Expediently, both combustion processes will occur at
different operating points in an engine application. In this
context, preferably the transitions between the combustion
processes are fluid, so that the two combustion processes are
treated as virtually equivalent.
[0010] In the HCCI or (p)HCCI operating mode, the combustion engine
may be operated respectively in a steady-state or quasi
steady-state manner. In the quasi steady-state operation, the
combustion engine carries out only slow operating-point changes. In
that case, the dynamic power component of the drive is provided by
the electric motor. In a conventional combustion process of the
diesel engine, in dynamic operation, fuel is injected into the
combustion chamber even after ignition has begun. This combustion
process may be used in different load ranges.
[0011] In a further advantageous method operation, to adjust an
increased power output in steady-state operation of the combustion
engine, it is not fired for a brief time and is pulled by the
electric motor to a new operating point. While the combustion
engine is being pulled, preferably an air-side charge cycle of the
combustion air of the combustion engine is optimized for the new
operating point. In the case of a diesel engine, it may also be
operated at the new operating point with parameters favorable for
the HCCI operation or (p)HCCI operation.
[0012] In another advantageous method operation, the combustion
engine is operated in quasi steady-state to set an increased power
output. In this case, only highly dynamic motive components are
compensated for by the electric motor in the HCCI or (p)HCCI
operating mode. Preferably, the steady-state or quasi steady-state
operation of the combustion engine is set in a part-load range of
the combustion engine, while the dynamic operation of the
combustion engine is set in a high-load range and/or full-load
range and/or at high speeds of the combustion engine.
[0013] In a hybrid vehicle according to the present invention
having at least one combustion engine, where at least one electric
motor for providing drive assistance is able to be activated at
least intermittently in a normal driving mode having a requested
drive power, the dynamic operation of the combustion engine is set
in a high-load range and/or full-load range and/or at high speeds
of the combustion engine.
[0014] Further specific embodiments, aspects and advantages of the
present invention are also yielded, regardless of their combination
in claims and without restricting the generality, from an exemplary
embodiment of the invention described in the following with
reference to the drawing.
BRIEF DESCRIPTION OF THE DRAWING
[0015] The FIGURE shows a characteristics field of a combustion
engine with torque over the speed of the combustion engine for the
case of a diesel engine.
DETAILED DESCRIPTION
[0016] The FIGURE shows a characteristics field having torque
characteristics M of a combustion engine over its speed n based on
a diesel engine of a preferred hybrid vehicle whose total drive
train is set up and operated in such a way that emissions such as
CO.sub.2, nitrogen oxides and soot exhausted by the combustion
engine are as minimal as possible.
[0017] The diesel engine is preferably operated selectively in
serial or in parallel or in parallel-serial or in power-split mode
with the aid of two electric motors. To that end, a design known
per se, having a parallel hybrid including two electric motors and
having a torque converter lockup clutch, is favorable.
[0018] In this context, the diesel engine is operated either in
HCCI operating mode or (p)HCCI operating mode or in conventional
mode, depending on the required power output. At the same time, at
least one electric motor with high dynamics makes drive energy
available for boosting the vehicle. In the (p)HCCI operating mode,
the drive corresponds to that of a parallel hybrid drive.
[0019] In the (p)HCCI process, the diesel fuel is injected directly
into a combustion chamber of the diesel engine, and the fuel-air
mixture developing in the combustion chamber is only ignited when
virtually the total fuel quantity needed for the engine cycle in
question has been injected into the respective combustion chamber.
Only a small quantity of fuel is still injected after the
ignition.
[0020] The hatched area is intended to indicate the area in which
the diesel engine is running in steady-state operation in the HCCI
operating mode, and the dynamic performance of the drive train is
improved by electromotive assistance. Since the HCCI combustion
process is controlled on the combustion-air side, the dynamics with
respect to the combustion of the fuel, especially during an engine
load change, are restricted. Moreover, the special mixture
formation, particularly in the part-load range, must be produced
with sufficient reliability.
[0021] In the high-load range, full-load range and/or at high
engine speeds, the diesel engine is operated with a conventional
combustion process, in which fuel is still injected after the
beginning of the combustion of the fuel in the combustion
chamber.
[0022] Moreover, a rapid transition may be achieved between the
operating mode using the (p)HCCI combustion process and the
conventional combustion process, in that the diesel engine is
pulled to a suitable operating point by the electric motor.
[0023] Preferably an electric motor having 20 to 50 kW is used for
an automobile.
[0024] Area 1 in the FIGURE indicates that HC and CO emissions may
be prevented by the parallel hybrid drive in the quasi steady-state
(p)HCCI operating mode of the diesel engine at low exhaust-gas
temperatures, as a result of a low torque at low speed of the
diesel engine. Area 2 indicates that the dynamic performance may be
improved by using the electric motor in the HCCI operating mode of
the diesel engine. Area 3 in the FIGURE indicates that the
operating point of the diesel engine in the HCCI operating mode may
be switched by the electric motor in that it pulls the diesel
engine, that is, in which in the (p)HCCI operating mode, the
combustion engine effects slow changes of the operating point. Area
4 indicates how the electric motor is able to improve the power
output of the drive train while the diesel engine is running in the
(p)HCCI operating mode with favorable emission behavior. Area 5
indicates how the transition between operation with the (p)HCCI
combustion process and the conventional combustion process is
improved. In this context, operation of the diesel engine with the
lowest emissions may be achieved in each instance by the (p)HCCI
operating mode.
[0025] In area 6, the diesel engine is operated with a conventional
combustion process, the electric motor assisting the diesel engine
so that it is able to run with optimized parameters.
Advantageously, it follows here that the energy store is small,
since only boost functions are assisted electromotively. A battery
with 0.5-1 kWh may be sufficient for the electric motor having
20-50 kW.
* * * * *